Antenna system with feed antenna

Abstract

The invention relates to an antenna system for coupling intended radio signals to the outside of a metal or shielding enclosure by configuring a first antenna (e.g., PIFA-type antenna) as a feed structure of a second antenna (e.g., slot-type antenna). Thereby, the first antenna can be used as an excitation of the second antenna, e.g., to couple the intended radio signals through the barrier of a shielded enclosure. In an example, the first antenna may be a standard PIFA-type antenna that is modified to create an extension and the reference planes of the first and second antennas are capacitively coupled so that the extended PIFA-type antenna can be used as microstrip excitation of a second antenna.

Description

[0001] 2025PF80009

[0002] 1

[0003] ANTENNA SYSTEM WITH FEED ANTENNA

[0004] FIELD OF THE INVENTION

[0005] The invention relates to the field of antenna systems for wireless communication in radio systems with metal enclosures (e.g., lighting systems, such as - but not limited to - solid-state lighting systems or other communication systems), for use in various different applications for home, office, retail, hospitality and industry.

[0006] BACKGROUND OF THE INVENTION

[0007] A luminaire can be any type of lighting unit or lighting fixture which comprises one or more light sources (e.g., visible or non-visible (infrared (IR) or ultraviolet (UV)) light sources) for illumination and / or communication purposes and optionally other internal and / or external parts necessary for proper operation of the lighting, e.g., to distribute the light, to position and protect the light sources and ballast (where applicable), and to connect the luminaires to a power supply. A radio module (with antenna) can be arranged in the power supply (e.g., a driver with enclosure) which may or may not be in the luminaire.

[0008] Solid-state lighting (SSL) is a type of lighting that uses semiconductor lightemitting diodes (LEDs), organic light-emitting diodes (OLED), or polymer light-emitting diodes (PLED) as sources of illumination rather than electrical filaments, plasma (used in arc lamps such as fluorescent lamps), or gas. Solid state electroluminescence is used in SSL, as opposed to incandescent bulbs (which use thermal radiation) or fluorescent tubes. Compared to incandescent lighting, SSL creates visible light with reduced heat generation and less energy dissipation.

[0009] Many luminaires of various types such as office, street and so-called design home luminaires basically consist of metal enclosures. These enclosures form Faraday cases and shield electromagnetic radiation from the enclosed volume to the outside world.

[0010] Although a luminaire housing may be open for light to exit, the cavity can still be electromagnetically shielded by metal on an LED board, thereby forming a completely encapsulating metal enclosure. From an electromagnetic compatibility perspective this may be beneficial, as it provides a shielding barrier. However, it also blocks intended radio signals to and from internal radio module(s) used for smart lighting connectivity. Thus, metal2025PF80009

[0011] 2

[0012] enclosures of luminaires shield intended radio signals of internal radio modules, rendering them ineffective for communication over practical distances. Conventional solutions for enabling electromagnetic coupling through this barrier are mostly based on making large enough windows in the enclosures to allow the radio signal to radiate through. Such an approach requires precise placement of internal antenna(s) relative to the window and strict control over the locations of other components such as wires inside the enclosure. It also results in aesthetically unacceptable, large holes in the enclosure.

[0013] SUMMARY OF THE INVENTION

[0014] It is an object of the present invention to facilitate bidirectional transmission of radio signals through metal enclosures.

[0015] This object is achieved by an antenna device as claimed in claim 1, by an antenna system as claimed in claim 6, by a luminaire as claimed in claim 11, and by a manufacturing method as claimed in claim 12.

[0016] According to a first aspect, an antenna device is provided, that comprises a first antenna having a coupling extension for configuring the first antenna as a direct feeding element of a second antenna, wherein a reference plane of the first antenna is configured to be capacitively coupled to a reference plane of the second antenna.

[0017] Furthermore, according to a second aspect, an antenna system comprising a first antenna coupled to a second antenna via a coupling extension is provided, wherein the first antenna is configured by the coupling extension as a direct feeding element of the second antenna, and wherein a reference plane of the first antenna is capacitively coupled to a reference plane of the second antenna.

[0018] Additionally, according to a third aspect, a luminaire comprising an antenna device of the first aspect or an antenna system of the second aspect is provided.

[0019] Moreover, according to a fourth aspect, a method of manufacturing an antenna device is provided, wherein the method comprises:

[0020] providing a first antenna with a coupling extension;

[0021] capacitively coupling a reference plane of the first antenna to a reference plane of a second antenna; and

[0022] configuring the coupling extension of the first antenna as direct feeding element of the second antenna.

[0023] Accordingly, a strong coupling between the first and second reference-plane dependent or unbalanced antennas can be provided by configuring the first antenna as a direct2025PF80009

[0024] 3

[0025] feeding element (or direct excitation element) of the second antenna, thereby avoiding strict control over the locations of other components such as wires inside a cavity or housing in which the first antenna is arranged. The structural requirements for configuring the first antenna as feeding element (e.g., capacitive coupling of the respective reference planes by pressing the first reference plane (e.g., a circuit board) against the second reference (cavity wall)) can be configured to exclude the possibility of other objects in the cavity getting into the coupling region, e.g., by configuring a coupling volume to exclude introducing (interfering) objects into this coupling volume. The dependence on the critical relative positions of placement of the two antennas is thereby alleviated, and so is the dependence on fixing and ensuring the exact locations of other components in the enclosure, such as wires. The increased coupling also implies much stronger coupling through the barrier (e.g., metal housing), resulting in enhanced range and robustness of the radio link. According to a first option of any of the first to fourth aspects, the first antenna may be a planar inverted F antenna (PIFA), and wherein the second antenna may be a slot-type antenna.

[0026] According to a second option of any of the first to fourth aspects, which may be combined with the first option, the coupling extension may be configured as an extended tip of a blade of the PIFA, wherein the extended tip may be configured to extend the blade beyond the reference plane of the PIFA, and wherein the extended tip may be reactively coupled to the plane containing the slot-type antenna to form a microstrip feed.

[0027] According to a third option of any of the first to fourth aspects, which may be combined with the first option, the coupling extension may be configured as an extended tip of a meandering portion of the PIFA, wherein the extended tip may be configured to extend the meandering portion beyond the reference plane of the PIFA, and wherein the extended tip may be reactively coupled to the (reference) plane of the slot-type antenna.

[0028] In the second and third options, the metal plane (e.g., housing wall) of the slot antenna also becomes the reference plane for the extended tip as a microstrip feed trace). According to a fourth option of any of the first to fourth aspects, which may be combined with any one of the first to third options, the (reference) plane of the slot-type antenna may be a metal wall in which the slot-type antenna is provided, wherein the extended tip may form a microstrip excitation for the slot-type antenna.

[0029] According to a fifth option of any of the first to fourth aspects, which may be combined with any of the first to fourth options, the slot-type antenna may be provided in a metallic housing of a luminaire or other device (e.g., mobile phone, laptop, medical device etc.).2025PF80009

[0030] 4

[0031] It shall be understood that the antenna device of claim 1, the antenna system of claim 6, the luminaire of claim 11 and the method of claim 12 may have similar and / or identical preferred embodiments, in particular, as defined in the dependent claims.

[0032] It shall further be understood that a preferred embodiment of the invention can also be any combination of the dependent claims or above embodiments with the respective independent claim.

[0033] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

[0034] BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In the following drawings:

[0036] Fig. 1 shows schematically a luminaire with LED module and transmission window;

[0037] Fig. 2 shows schematically a block diagram of an antenna system with coupled antennas according to various embodiments;

[0038] Fig. 3 shows schematically a partial luminaire wall with excitation of a slot antenna by a modified planar inverted-F antenna according to an embodiment; and

[0039] Fig. 4 shows schematically a diagram with an SI 1 parameter curve of the coupled antenna system according to the embodiment.

[0040] DETAILED DESCRIPTION OF EMBODIMENTS

[0041] Various embodiments of the present invention are now described, which are applicable to luminaires of a solid-state lighting system, such as semiconductor LEDs, semiconductor lasers, vertical -cavity surface emitting lasers (VCSELs), organic lightemitting diodes (OLED), or polymer light-emitting diodes (PLED) as sources of illumination or light sources in visible or non-visible light spectra.

[0042] More specifically, the following embodiments are directed to LED luminaires. They can be implemented in connection with any type of LED module or board and are applicable to various kinds of luminaires, e.g., connected or non-connected luminaires for indoor (e.g., home or office lighting, etc.) or outdoor area (e.g., streetlights, stadium lighting, etc.).

[0043] It is noted that - throughout the present disclosure - the structure and / or function of blocks or circuit components with identical reference numbers that have been described before are not described again, unless an additional specific functionality is2025PF80009

[0044] 5

[0045] involved. Moreover, only those structural elements and functions are shown, which are useful to understand the embodiments. Other structural elements and functions are omitted for brevity reasons.

[0046] Fig. 1 shows schematically a luminaire 100 with LED module 140 and transmission window 120.

[0047] The luminaire 100 may be a commercial luminaire with metal housing, wherein an optical window provided for the LED module 140 may be effectively “closed” (i.e., shielded) for electromagnetic radiation due to metal provided on an LED board of the LED module.

[0048] The transmission window 120 is therefore required for allowing a use of internal radio modules of e.g. wireless drivers or sensor modules or control or communication elements of the luminaire 100. Such radio modules use various types of antennas (such as etched trace antennas) that are conventionally tuned for operation in plastic luminaires. If these were to be used to radiate through the transmission window 120 in the shielded luminaire 100, their efficiency would be very low (easily 20 dB less in power), resulting in low communication robustness.

[0049] This problem may be solved by providing a second antenna (e.g., a slot-type antenna) in the metal housing and placing the radio module within the metal housing (enclosure) such that the first antenna (e.g., etched trace antenna) excites the second antenna.

[0050] The length of such a slot of the slot antenna may approximate half a wavelength, i.e., about 57 mm at a transmission frequency of 2.4 GHz. The internal first antenna of the luminaire may be placed at some distance from the second antenna to excite it with its primary fields.

[0051] Conventionally, an antenna trying to radiate through the transmission window 120 in the wall was used, where the antenna and the transmission window 120 were not tightly coupled. This typically results in a large distance between the antenna and the transmission window 120, wherein electromagnetic fields of a standing wave pattern created by the antenna in the metal housing can be tuned to escape through the transmission window 120. However, changing the position of a wire or other metal part in the metal housing will then change the standing wave pattern and the electromagnetic fields are no longer tuned to escape through the window.

[0052] In other conventional solutions, the transmission window 120 was configured as a second antenna (slot antenna) by tuning its shape and dimensions. The internal first antenna could then be reactively coupled through its near fields (non-radiation fields) to this2025PF80009

[0053] 6

[0054] additional second antenna in the wall. Thereby, moving metal objects in the enclosure will now have less effect on this coupling because it is a direct coupling that is not dependent on the cavity of the enclosure. However, the separation distance between the first antenna and the second antenna typically corresponds to fractions of a wavelength, which requires precise placement of the first antenna relative to the second antenna and strict control over the locations of other components such as wires inside the metal housing. As a result, such a conventional solution with near-field coupling is inherently unstable due to a strong dependency on the exact relative positions of the two antennas and the location of all other metal components in the metal housing. The reactive coupling requires accurate, short range, and fixed placement of the two antennas with respect to each other.

[0055] In the following, embodiments for improved coupling with more degrees of freedom are described.

[0056] Fig. 2 shows schematically a block diagram of an antenna system with coupled antennas according to various embodiments.

[0057] The proposed antenna system has an improved antenna design with two antennas and a coupling element (CE) 20, wherein a first antenna (Al) 10 is configured to generate a radio signal based on an output signal of an internal radio module arranged within a metal housing, a second antenna (A2) 30 (e.g., a slot-type antenna) is configured to emit the radio signal outside the metal housing, and the coupling element (CE) 20 is configured to enhance the first antenna 10 to be used as an excitation or feed element of the second antenna 30 to directly couple the radio signal through the barrier of a shielded enclosure. The first antenna 10 may be a etched trace antenna (e.g., monopole or unbalanced antenna) comprising an elongated or polygonal or meandering conductor driven with respect to some type of conductive surface, called a reference plane.

[0058] The coupling element 20 may be configured as a structural extension of the first antenna 10, that modifies the first antenna 10 to become a direct feeding element of the second antenna. The coupling element 20 may for example be configured as an extension or extra length (e.g., blade) of the first antenna 10 that directly couples the radio signal e.g. as a waveguide or in a waveguide manner as a transmission line into the second antenna 30.

[0059] In an embodiment, the proposed antenna system can be manufactured by modifying a first (standard) a planar inverted F antenna (PIFA) 10 to have an extension or other structural coupling element 20. Furthermore, a reference plane of the first antenna 10 is arranged to be capacitively coupled to a reference plane containing the second antenna 30 (which may be a slot-type antenna). The coupling element 20 of the first antenna 10 is then2025PF80009

[0060] 7

[0061] configured as a microstrip excitation of a second (slot) antenna 30. Thereby, the radio signal of the first antenna 10 is guided through the microstrip of the coupling element 20 as excitation into the second antenna 30.

[0062] The PIFA is a type of antenna used in wireless communication, mainly at ultra-high frequency (UHF) and microwave frequencies. It consists of a monopole antenna (unbalanced) running parallel to a reference plane and connected to it at one end. The antenna is fed from an intermediate point a distance from the connected end. Such a design has advantages over a simple monopole antenna in that the PIFA is shorter and more compact (allowing it to be contained within the case of a luminaire or other mobile device) and can be impedance-matched to a feed circuit by the designer, allowing it to radiate power efficiently without the need for extraneous matching components. The input impedance of the PIFA is dependent on the distance of the feed point from the connected end. The portion of the antenna between the feed point and the reference plane is essentially behaving as a short-circuit stub. Thus, the designer can match the antenna to the feedline impedance by setting the position of the feed point along the antenna element.

[0063] PIFAs can be printed using a microstrip etching process, a widely used technology that allows printed radio frequency (RF) components to be manufactured as part of the same printed circuit board used to mount other components.

[0064] PIFAs are an example of an etched trace antenna. Many variants of this, and other forms of the inverted-F, exist that implement wideband or multi-band antennas.

[0065] Techniques include coupled resonators and the addition of slots.

[0066] A printed PIFA can be implemented in the classic inverted-F shape, usually to one side of the circuit board where the reference plane has been removed from underneath the antenna.

[0067] Another variation of the first antenna 10 may be a meandered inverted-F antenna (MIFA). Where there is insufficient board space to extend an antenna to the full required length, the antenna may be meandered to reduce its physical length while retaining its designed electrical length. This can be compared to the spiraling of an antenna as found in rubber ducky antennas.

[0068] Fig. 3 shows schematically a partial luminaire wall with excitation of a slot antenna 50 by a modified PIFA 40 according to an embodiment.

[0069] The PIFA 40 is connected to an internal radio module and operates as normal in the absence of the metal luminaire. It consists of an elongated antenna element (blade) that can be straight or meandered, the latter allowing the PIFA 40 to be made more compact. It2025PF80009

[0070] 8

[0071] also has a fairly large reference plane 74 against which it is excited. The reference plane 74 contributes to the radiation.

[0072] In the proposed implementation according to the embodiment, an outer metal wall 90 of the luminaire, a plastic wall 80 of the radio module, a dielectric layer 72 of a printed circuit board (PCB) 70 of the radio module, and the reference plane 74 of the PCB 70 are tightly stacked so that they form a continuous "sandwich" with touching surfaces.

[0073] The PIFA 40 is fed by a signal source 60 of a radio chip provided on the PCB 70 via a feeding extension 44 at an intermediate point located at a distance from a shortcut extension 46 at a connected end.

[0074] The proposed structure allows to directly feed the slot antenna 50 by operating the PIFA 40 as a direct microstrip transmission line feed (waveguide), referenced to the metal wall 90, for the slot antenna 50.

[0075] The PIFA 40 is modified to have a tip 42 (extension) extending past its own reference plane 74. This tip 42 together with the rest of the PIFA blade can be used to form a transmission line referenced to the enclosure wall and coupled to the slot antenna 50 at the tip section. The unconventional extension (tip 42) of the blade of the PIFA 40 extends past the edge of its own reference plane 74 and is subsequently tightly coupled (close placement) to the slot antenna 50 in the metal wall 90 of the luminaire enclosure. Thereby, the tip 42 (together with the PIFA blade) forms a microstrip line with the metal wall 90 as reference. Actually, the tip 42 is also coupled to the original reference plane of the PIFA 40 so that a continuous microstrip line from the radio module output right to the slot antenna 50 is formed.

[0076] If the blade of the PIFA 40 is meandered, the tip 42 (e.g., last few millimeters) of the blade extending past the reference plane is straight.

[0077] Note that the proposed modified PIFA 40 still works well as radiator element only in the same radio module used in plastic luminaires. Thus, the proposed configuration facilitates provision of a single stock keeping unit (SKU) module that operates well in metal-free environments using just the PIFA 40 alone and robustly in metal enclosures in combination with the slot antenna 50 in the luminaire enclosure.

[0078] The radio module may be mounted in a plastic enclosure in such a way that the reference plane 74 and the blade of the PIFA 40 are pressed tightly against the plastic wall 80 of the module encapsulation.2025PF80009

[0079] 9

[0080] The plastic wall 80 may have a relative permittivity in the range of 2 to 2.5. Other materials with higher relative permittivity such as ceramics, glass, etc., may also be used.

[0081] The PIFA 40 may be correspondingly tuned in this location in order to be efficient as a stand-alone module for use in plastic luminaires. When the radio module is now tightly placed against the wall of the metal enclosure, the tip 42 and the blade of the PIFA 40 forms a transmission line referenced to the metal wall 90 of the enclosure of the luminaire. By closely stacking the radio module against the luminaire wall, the reference plane 74 of the PIFA 40 and the metal wall 90 are capacitively coupled, effectively becoming the same reference plane, so that the tip 42 and the blade are reactively coupled to the metal wall 90 to form a microstrip line. This coupling of the reference plane 74 of the PIFA 40 effectively enlarges the reference plane of the PIFA 40, thereby detuning the PIFA 40. This is however of no significance, as the PIFA 40 is not used as radiator anymore and the system bandwidth and center frequency are determined by the design of the slot antenna 50, i.e. slot dimensions and positioning of the feed (PIFA tip 42).

[0082] In an example, the slot height may be 2mm and it can be filled or covered with plastic. The slot may be designed to fit the PIFA 40 in the off-the-shelf wireless module with the latter designed to work in plastic luminaires.

[0083] The extended PIFA 40 with the tip 42 shows a frequency characteristic of its matching-related Sn parameter (reflection coefficient or return loss) with a double dip due to an extra mode introduced by the inhomogeneity of the tip 42. The two dips (minima) can be tuned (shifted against each other) by modifying the structure or feeding of the PIFA 40 to obtain either a broad matching bandwidth or an improved matching. The length of the tip 42 and its position on the slot can thus be used to tune the resonance frequency of the combination of the extended PIFA 40 and the slot antenna 50.

[0084] Fig. 4 shows schematically a frequency diagram with an SI 1 parameter curve 400 of the proposed coupled antenna system according to the embodiment for an exemplary implementation in an office luminaire, where the luminaire is provided with a completely closed metal box with a single slot antenna of size 57mm x 2mm that is fed as proposed by the extended tip 42 of a radio module of a modified wireless LED driver.

[0085] The curve 400 shows a robust behavior of the proposed antenna system with a bandwidth B between 2.212GHz and 2.258GHz. Two close dips are located at about 2.235GHz.2025PF80009

[0086] 10

[0087] To summarize, an antenna system for coupling intended radio signals to the outside of a metal or shielding enclosure has been described, wherein a first antenna (e.g., PIFA-type antenna) is configured as a feed structure of a second antenna (e.g., slot-type antenna). Thereby, the first antenna can be used as an excitation of the second antenna, e.g., to couple the intended radio signals through the barrier of a shielded enclosure. In an example, the first antenna may be a standard PIFA-type antenna that is modified to create an extension and the ground planes of the first and second antennas are capacitively coupled so that the extended PIFA-type antenna can be used as microstrip excitation of a second antenna.

[0088] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments concerning a combination of PIFA and slot antennas in luminaire housings. The first antenna may be any etched trace antenna driven against a reference plane, such as slender, strip-like, antenna (e.g., an etched monopole or whip). The second antenna may be any narrow, rectangular window, like a ventilation slot, in a conductive housing with shape and dimensions adapted to the transmission frequency of the radio signal.

[0089] The above embodiments may be implemented in (e.g., integrated or combined with) various high-efficiency products such as office luminaires, outdoor lighting, LED strips, color-tuneable spots or other smart or connected devices such as mobile phones, laptops or other mobile devices. The described challenge of module integration into metal housings applies to all the above types of devices where sensors, wireless driver(s) and / or other wireless communication modules have been integrated.

[0090] Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single processor or other unit may fulfil the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. The foregoing description details certain embodiments of the invention. It will be appreciated, however, that no matter how detailed the foregoing appears in the text, the invention may be practiced in many ways and is therefore not limited to the embodiments disclosed. It should be noted that the use of a particular terminology when describing certain2025PF80009

[0091] 11

[0092] features or aspects of the invention should not be taken to imply that the terminology is being re-defined herein to be restricted to include any specific characteristics of the features or aspects of the invention with which that terminology is associated.

[0093] A single unit or device may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

2025PF8000912CLAIMS:1 An antenna device comprising a first antenna (10) having a coupling extension (20) for configuring the first antenna (10) as a direct feeding element of a second antenna (30), wherein a reference plane (74) of the first antenna (40) is configured to be capacitively coupled to a reference plane (90) of the second antenna,wherein the first antenna (10) is a planar inverted F antenna, PIFA (40), and wherein the second antenna (30) is a slot-type antenna (50),wherein the coupling extension (20) is configured as an extended tip (42) of a blade of the PIFA (40), wherein the extended tip (42) is configured to extend the blade beyond the reference plane (74) of the PIFA (40), and wherein the extended tip (42) is reactively coupled or referenced to the reference plane (90) of the slot-type antenna (50) to form a microstrip feed trace.

2. The antenna device of claim 1, wherein the coupling extension (20) is configured as an extended tip (42) of a meandering portion of the PIFA (40), wherein the extended tip (42) is configured to extend the meandering portion beyond the reference plane (74) of the PIFA (40), and wherein the extended tip (42) is reactively coupled to the reference plane (90) of the slot-type antenna (50).

3. The antenna device of any of the preceding claims, wherein the reference plane (90) of the slot-type antenna (50) is a metal wall in which the slot-type antenna (50) is provided, and wherein the extended tip (42) forms a microstrip excitation for the slot-type antenna (50).

4. An antenna system comprising a first antenna (10) coupled to a second antenna (30) via a coupling extension (20), wherein the first antenna (10) is configured by the coupling extension (20) as a direct feeding element of the second antenna (30), and wherein a reference plane (74) of the first antenna (10) is capacitively coupled to a reference plane (90) of the second antenna (30).2025PF80009135. The antenna system of claim 4, wherein the first antenna (10) is a planar inverted F antenna, PIFA, (40), and wherein the second antenna (30) is a slot-type antenna (50).

6. The antenna system of claim 5, wherein the coupling extension (20) is configured as an extended tip (42) of a blade of the PIFA (40), wherein the extended tip (42) is configured to extend the blade beyond the reference plane (74) of the PIFA (40), and wherein the extended tip (42) is reactively coupled to the reference plane (90) of the slot-type antenna (50).

7. The antenna system of claim 5, wherein the coupling extension (20) is configured as an extended tip (42) of a meandering portion of the PIFA (40), wherein the extended tip (42) is configured to extend the meandering portion beyond the reference plane (74) of the PIFA (40), and wherein the extended tip (42) is reactively coupled to the reference plane (90) the slot-type antenna (50).

8. The antenna system of claim 6 or 7, wherein the reference plane of the slottype antenna (50) a metal wall (90) in which the slot-type antenna (50) is provided, and wherein the extended tip (42) forms a microstrip excitation for the slot-type antenna (50).

9. A luminaire comprising an antenna device of any one of claims 1 to 3 or an antenna system of any one of claims 4 to 8.

10. A method of manufacturing an antenna system, wherein the method comprises:providing a first antenna (40) with a coupling extension (42); capacitively coupling a reference plane (74) of the first antenna (40) to a reference plane (90) of a second antenna (50); andconfiguring the coupling extension (42) of the first antenna (40) as direct feeding element of the second antenna (50), wherein the first antenna (40) is a planar inverted F antenna, PIFA, wherein the second antenna (50) is a slot-type antenna, wherein the coupling extension of the first antenna (40) comprises a tip (42) configured as a microstrip excitation of the second antenna (50), and wherein the tip (42) is reactively coupled to the reference plane (90) of the slot-type antenna (50) to form a microstrip feed.2025PF800091411. The method of claim 10, further comprising providing the slot-type antenna (50) in a metallic housing of a luminaire (100).

Images